Polymer-based electroluminescent devices (PLEDs) have the potential for providing inexpensive alternatives to LEDs. PLEDs may be fabricated by coating the appropriate surfaces with the organic polymer, and hence, do not require the use of high cost fabrication systems such as those utilized in the fabrication of semiconductor devices. A simple PLED may be constructed from an electroluminescent layer sandwiched between an electron injection electrode and a hole injection electrode. More complicated devices utilize electron and hole transport layers between the above mentioned electrodes and the electroluminescent layer.
Unfortunately, the lifetimes obtained with current PLEDs are not sufficient to allow commercially useful devices. One of the most critical issues in organic electroluminescent devices is the decrease of performance (light output and efficiency) as a function of accumulated time of operation. While many strategies have been proposed and implemented to extend the useful lifetime of luminescent devices none of these strategies has resulted in devices with commercially attractive lifetimes.
Broadly, it is the object of the present invention to provide an improved PLED.
It is a further object of the present invention to provide a PLED with increased lifetime relative to prior art PLEDs.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.